The instant invention relates to bursting apparatus and more particularly to a clam shell housing for apparatus for bursting continuous webs of material along transverse lines of weakening.
Business forms are often preprinted on a continuous web of perforated material. Such forms are conventionally used in billing and other typical business transactions. The continuous series of forms require processing for end use, such as mailing, which may require bursting or separating the forms, as well as the performance of the end functions of stacking, stamping, sealing, inserting, collating (for additional enclosures) and folding. The aforesaid end functions are all provided for with existing equipment in one continuous process.
The bursting of the web is typically achieved with the use of two sets or pairs of rollers. The downstream rollers are made and arranged to be driven at a slightly higher speed than the upstream rollers, so that the web, when properly perforated, will separate. There is an additional element called a burst ball or burster roller located between the two pairs of rollers which assists the separation process, especially if the two rollers are running at the same speed and the upstream rollers are momentarily stopped to permit the downstream rollers to continue feeding the desired, separated sheet.
In the interest of greater efficiency and throughput, attempts have been made to feed two webs through a single pair of upstream (feeding) rollers so that two webs could be handled and burst alternately. The webs were offset by half a pitch or length of sheet being burst. The mechanical arrangement was as described hereinabove regarding rollers and the bursting element. The result was that the web lying in contact with the upper feed (upstream) roller, i.e. the upper web, would creep out of position due to the geometric relationship of the web in bending about the feed roller at the entry area. This creep results in the perforation on the upper web not being in the correct position when that web arrived at the bursting roller, which prevents the upper web from bursting properly at the correct time.
There have been several attempts to eliminate the creep problem, one of which requires an additional pair of feed rollers, so that two paper paths are created, one for each web. Obviously, for purposes of loading the web into the bursting apparatus and for clearing jams, the upper paper path poses no additional problems. However, the lower paper path, being beneath the upper paper path, does pose problems when it comes to loading the bursting apparatus for operation and when a jam occurs in the lower paper path. Prior art bursting devices which operate with dual web paths provide access for these purposes to the lower web only through the upper paper path or around other parts, which makes access for loading and jam clearance extremely difficult.
Accordingly, the instant invention provides a clam shell housing which permits the upper paper path to be pivoted away from the lower paper path, thereby providing complete access to the lower paper path without any interference from the upper paper path.